Characteristic Analysis on Human-Machine Interaction Force of Lower Limb Exoskeleton / 医用生物力学

Objective To propose a human-machine coupling dynamics modeling method based on virtual muscles, so as to quantitatively analyze the characteristics of human-computer interaction force and muscle activation of the musculoskeletal system. Methods First, in the gait experiment of wearing exoskeleton, the human motion capture system and self-developed mechanical monitoring device were used to obtain the wearer’s walking dynamics, electromyography (EMG) signals, exoskeleton drive status and local human-computer interaction information. The human-machine coupling model was established in modeling environment of the bone system, and the gait experiment data and the exoskeleton joint torques were used as driving information of the coupling model to perform inverse mechanical calculations. Finally, by adjusting strength and stiffness parameters of the virtual muscles, the real data of the model was compared with the experimental test result, to quantitatively evaluate effectiveness of the human-machine coupling model of the lower extremity exoskeleton. Results The normal interaction force calculated by inverse dynamics of the coupled model and the activation of lower limb muscles had a good consistency in response curve trend compared with measurement results of the gait experiment, and the interaction force results had a high degree of correlation (r=0.931, P<0.01), the root mean square error was small, and the peak error of lower limb muscle activation was lower than 5%. Conclusions The human-machine coupling model proposed in this study can effectively calculate the interaction force between human and exoskeleton. The establishment of the coupling model provides a theoretical basis for verification and iteration of the exoskeleton structure optimization and control algorithm, as well as performance evaluation on mobility assistance effects of the exoskeleton.

Study on the influence of wearable lower limb exoskeleton on gait characteristics / 生物医学工程学杂志

The purpose of this paper was to investigate the effects of wearable lower limb exoskeletons on the kinematics and kinetic parameters of the lower extremity joints and muscles during normal walking, aiming to provide scientific basis for optimizing its structural design and improving its system performance. We collected the walking data of subjects without lower limb exoskeleton and selected the joint angles in sagittal plane of human lower limbs as driving data for lower limb exoskeleton simulation analysis. Anybody (the human biomechanical analysis software) was used to establish the human body model (the human body model without lower limb exoskeleton) and the man-machine system model (the lower limb exoskeleton model). The kinematics parameters (joint force and joint moment) and muscle parameters (muscle strength, muscle activation, muscle contraction velocity and muscle length) under two situations were compared. The experimental result shows that walking gait after wearing the lower limb exoskeleton meets the normal gait, but there would be an occasional and sudden increase in muscle strength. The max activation level of main lower limb muscles were all not exceeding 1, in another word the muscles did not appear fatigue and injury. The highest increase activation level occurred in rectus femoris (0.456), and the lowest increase activation level occurred in semitendinosus (0.013), which means the lower limb exoskeletons could lead to the fatigue and injury of semitendinosus. The results of this study illustrate that to avoid the phenomenon of sudden increase of individual muscle force, the consistency between the length of body segment and the length of exoskeleton rod should be considered in the design of lower limb exoskeleton extremity.

Sistema de biofeedback para rehabilitación de marcha asistida por un exoesqueleto / Biofeedback System for Exoskeletqn Assisted Gait Rehabilitation / Sistema de biofeedback para reabilitação de marcha assistida por um exoesqueleto

Resumen Los robots proporcionan nuevas formas de terapia para pacientes con desórdenes neurológicos. Las terapias de marcha asistidas con exoesqueletos pueden incrementar la duración y la intensidad de los entrenamientos para los pacientes y reducir el esfuerzo físico del terapeuta. Sin embargo, el uso de estos dispositivos para el entrenamiento de la marcha limita la interacción física entre el terapeuta y el paciente, en comparación con la terapia manual. Una apropiada realimentación de las funciones corporales y biomecánicas en la interacción con el sistema robótico facilita la evaluación del desempeño del paciente, motivándolo en el reaprendizaje de la marcha con resultados superiores. Este artículo presenta el diseño de una interfaz de usuario para un exoesqueleto de miembros inferiores para asistencia en la marcha y en terapias de rehabilitación. Se consideraron aspectos técnicos y clínicos para proporcionar ventajas del exoesqueleto durante las terapias, estableciendo una herramienta de apoyo para la configuración, monitoreo y registro de los parámetros involucrados. Se propuso un esquema de realimentación sensorial para el paciente acerca de la actividad muscular, la presión ejercida en diferentes puntos de los pies y algunas variables biomecánicas. Finalmente, se valida la herramienta con sujetos sanos por medio de un test de usabilidad propuesto.

Abstract The inclusion of robots in rehabilitation allow advantages for generate newer therapies in neurologic disorder patients. Assistive gait therapies using robots, like exoskeletons, allow increase the time and intensity training for patients while the strenuous labor of therapist is reduced. However, the physic interaction between therapist and patient in training with robots is limited, in relation to the traditional manual therapy. An appropriated feedback of biological and biomechanics functions in the robot interaction during training provides an easier performance evaluation of the patient for the therapist. Further, biofeedback gives a motivation to the patient and encourages him for gait relearning with higher effects than conventional. This paper presents a user interface design for a lower limb exoskeleton for human gait assistance in rehabilitation. Clinical and technical criteria for increasing the advantages of the exoskeleton in therapy were considered. A biofeedback scheme about muscle activity, plantar pressure and some biomechanics variables, for the patient is proposed. Finally, a validation for this tool with healthy subjects by a usability test was carried out.

Resumo A inclusão de robôs na reabilitação fornecem vantagens que promovem novas formas de terapia em pacientes com desordens neurológicas. Terapias de marcha assistidas por exoesqueletos permitem o aumento da duração e da intensidade dos exercícios com os pacientes, reduzindo o esforço físico dos terapeutas. Não entanto, o uso desses dispositivos para o treino da marcha limita a interação física entre o terapeuta e paciente, em comparação com a terapia manual. Uma apropriada realimentação das funções corporais e biomecânicas na interação com o sistema robótico facilita a avaliação do progresso do paciente, motiva e incentiva ao paciente na reaprendizagem da marcha gerando efeitos superiores aos convencionais. Neste artigo apresenta-se o desenho de uma interface de usuário para um exoesqueleto de membros inferiores para assistência na marcha e nas terapias de reabilitação. São considerados aspectos técnicos e clínicos para fornecer maiores vantagens do exoesqueleto durante as terapias, estabelecendo uma ferramenta de suporte para configuração, monitoramento e registro dos parâmetros envolvidos. Foi proposto um sistema de realimentação sensorial para o paciente sobre a atividade muscular, a pressão em diferentes pontos dos pés e algumas variáveis biomecânicas. Finalmente, é apresentada a ferramenta de validação para indivíduos saudáveis utilizando um teste de usabilidade proposto.